215 research outputs found
Microencapsulation technology by nature: Cell derived extracellular vesicles with therapeutic potential
Cell derived extracellular vesicles are submicron structures surrounded by phospholipid bilayer and released by both prokaryotic
and eukaryotic cells. The sizes of these vesicles roughly fall into the size ranges of microbes, and they represent efficient delivery
platforms targeting complex molecular information to professional antigen presenting cells. Critical roles of these naturally formulated
units of information have been described in many physiological and pathological processes. Extracellular vesicles are not only
potential biomarkers and possible pathogenic factors in numerous diseases, but they are also considered as emerging therapeutic
targets and therapeutic vehicles. Strikingly, current drug delivery systems, designed to convey therapeutic proteins and peptides
(such as liposomes), show many similarities to extracellular vesicles. Here we review some aspects of therapeutic implementation
of natural, cell-derived extracellular vesicles in human diseases. Exploration of molecular and functional details of extracellular
vesicle release and action may provide important lessons for the design of future drug delivery systems
Length scale dependence of dynamical heterogeneity in a colloidal fractal gel
We use time-resolved dynamic light scattering to investigate the slow
dynamics of a colloidal gel. The final decay of the average intensity
autocorrelation function is well described by , with and
decreasing from 1.5 to 1 with increasing . We show that the dynamics is not
due to a continuous ballistic process, as proposed in previous works, but
rather to rare, intermittent rearrangements. We quantify the dynamical
fluctuations resulting from intermittency by means of the variance
of the instantaneous autocorrelation function, the analogous of
the dynamical susceptibility studied in glass formers. The amplitude
of is found to grow linearly with . We propose a simple --yet
general-- model of intermittent dynamics that accounts for the dependence
of both the average correlation functions and .Comment: Revised and improved, to appear in Europhys. Let
Magnetic Fluctuations and Correlations in MnSi - Evidence for a Skyrmion Spin Liquid Phase
We present a comprehensive analysis of high resolution neutron scattering
data involving Neutron Spin Echo spectroscopy and Spherical Polarimetry which
confirm the first order nature of the helical transition and reveal the
existence of a new spin liquid skyrmion phase. Similar to the blue phases of
liquid crystals this phase appears in a very narrow temperature range between
the low temperature helical and the high temperature paramagnetic phases.Comment: 11 pages, 16 figure
Dynamics in shear flow studied by X-ray Photon Correlation Spectroscopy
X-ray photon correlation spectroscopy was used to measure the diffusive
dynamics of colloidal particles in a shear flow. The results presented here
show how the intensity autocorrelation functions measure both the diffusive
dynamics of the particles and their flow-induced, convective motion. However,
in the limit of low flow/shear rates, it is possible to obtain the diffusive
component of the dynamics, which makes the method suitable for the study of the
dynamical properties of a large class of complex soft-matter and biological
fluids. An important benefit of this experimental strategy over more
traditional X-ray methods is the minimization of X-ray induced beam damage.
While the method can be applied also for photon correlation spectroscopy in the
visible domain, our analysis shows that the experimental conditions under which
it is possible to measure the diffusive dynamics are easier to achieve at
higher q values (with X-rays).Comment: 9 pages, 7 figures, to appear in Eur. Phys. J.
X-ray Near Field Speckle: Implementation and Critical Analysis
We have implemented the newly-introduced, coherence-based technique of x-ray
near-field speckle (XNFS) at 8-ID-I at the Advanced Photon Source. In the near
field regime of high-brilliance synchrotron x-rays scattered from a sample of
interest, it turns out, that, when the scattered radiation and the main beam
both impinge upon an x-ray area detector, the measured intensity shows
low-contrast speckles, resulting from interference between the incident and
scattered beams. We built a micrometer-resolution XNFS detector with a high
numerical aperture microscope objective and demonstrate its capability for
studying static structures and dynamics at longer length scales than
traditional far field x-ray scattering techniques. Specifically, we
characterized the structure and dynamics of dilute silica and polystyrene
colloidal samples. Our study reveals certain limitations of the XNFS technique,
which we discuss.Comment: 53 pages, 16 figure
Histamine deficiency promotes inflammation-associated carcinogenesis through reduced myeloid maturation and accumulation of CD11b \u3csup\u3e+\u3c/sup\u3eLy6G\u3csup\u3e+\u3c/sup\u3e immature myeloid cells
Histidine decarboxylase (HDC), the unique enzyme responsible for histamine generation, is highly expressed in myeloid cells, but its function in these cells is poorly understood. Here we show that Hdc-knockout mice show a high rate of colon and skin carcinogenesis. Using Hdc-EGFP bacterial artificial chromosome (BAC) transgenic mice in which EGFP expression is controlled by the Hdc promoter, we show that Hdc is expressed primarily in CD11b +Ly6G+ immature myeloid cells (IMCs) that are recruited early on in chemical carcinogenesis. Transplant of Hdc-deficient bone marrow to wild-type recipients results in increased CD11b + Ly6G + cell mobilization and reproduces the cancer susceptibility phenotype of Hdc-knockout mice. In addition, Hdc-deficient IMCs promote the growth of tumor allografts, whereas mouse CT26 colon cancer cells downregulate Hdc expression through promoter hypermethylation and inhibit myeloid cell maturation. Exogenous histamine induces the differentiation of IMCs and suppresses their ability to support the growth of tumor allografts. These data indicate key roles for Hdc and histamine in myeloid cell differentiation and CD11b+Ly6G+IMCs in early cancer development. © 2011 Nature America, Inc. All rights reserved
Skyrmions and spirals in MnSi under hydrostatic pressure
The archetype cubic chiral magnet MnSi is home to some of the most
fascinating states in condensed matter such as skyrmions and a non-Fermi liquid
behavior in conjunction with a topological Hall effect under hydrostatic
pressure. Using small angle neutron scattering, we study the evolution of the
helimagnetic, conical and skyrmionic correlations with increasing hydrostatic
pressure. We show that the helical propagation vector smoothly reorients from
to at intermediate pressures. At
higher pressures, above the critical pressure, the long-range helimagnetic
order disappears at zero magnetic field. Nevertheless, skyrmion lattices and
conical spirals form under magnetic fields, in a part of the phase diagram
where a topological Hall effect and a non-Fermi liquid behavior have been
reported. These unexpected results shed light on the puzzling behavior of MnSi
at high pressures and the mechanisms that destabilize the helimagnetic
long-range order at the critical pressure
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